SANAA, Yemen -- Thousands of defiant Yemenis continued Wednesday with their sit-in at a public square near Sanaa university, a day after the army stormed its campus, firing rubber bullets and tear gas in an attack that left one person dead and scores of others wounded.

The attack escalated tensions in Yemen, which has been rocked by weeks of protests against President Ali Abdullah Saleh, a key U.S. ally in the campaign against al-Qaida who has been in power 32 years.

Abdullah al-Jeifi, 24, died and several other protesters who were shot in Tuesday's raid were in serious condition, said Mohammed al-Abahi, one of the doctors volunteering at the Sanaa University campus.

Outraged at the government raid, more protesters camped out in tents near the university and on campus Wednesday. A group of young protesters issued a "black list" with the names of 13 officials they say are responsible for the violence against peaceful protesters. The names include the son of President Ali Abdullah Saleh who heads the Republican Guards, the interior minister and other top security officials.

The statement vowed revenge against those they called "criminals" and pledged to continue with the sit-in until they topple the regime. Thousands of people also protested in the southern port city of Aden and on the streets of Ibb province.

Human rights groups and the U.S. criticized Yemen's crackdown on protests Wednesday.

In Washington, State Department spokesman Mark Toner called on both sides to show restraint. "We urge the government of Yemen to investigate and hold accountable those who appear to have utilized excessive force," he said.

"These disturbing heavy-handed tactics used with lethal effect against protesters must stop immediately. People must be allowed to assemble and protest in peace," said Philip Luther, Amnesty International's deputy director for the Middle East and North Africa.

Human Rights Watch also issued a report, saying Yemeni security forces killed at least nine people and injured 150, some of them children, during peaceful protests in the southern city of Aden last month.

"Shooting into crowds is no way to respond to peaceful protests," said Joe Stork, deputy Middle East and North Africa director at Human Rights Watch.

Students at Sanaa University have been sleeping on campus since mid-February, shortly after the start of the protests calling on Saleh to step down. In an escalation, soldiers stormed the campus late on Tuesday, shooting live ammunition, rubber bullets and firing tear gas. About 90 protesters sustained gas inhalation and minor injuries in the raid.

"This aggression is an indication that the regime is collapsing and cannot stand before the youth revolution," said Mohammad Qahtan, a spokesman for the opposition.